Loss of HAI-2 in mice with decreased prostasin activity leads to an early-onset intestinal failure resembling congenital tufting enteropathy.

Prostasin (CAP1/PRSS8) is a glycosylphosphatidylinositol (GPI)-anchored serine protease that is essential for epithelial development and overall survival in mice. Prostasin is regulated primarily by the transmembrane serine protease inhibitor, hepatocyte growth factor activator inhibitor (HAI)-2, and loss of HAI-2 function leads to early embryonic lethality in mice due to an unregulated prostasin activity. We have recently reported that critical in vivo functions of prostasin can be performed by proteolytically-inactive or zymogen-locked variants of the protease. Here we show that the zymogen form of prostasin does not bind to HAI-2 and, as a result, loss of HAI-2 does not affect prenatal development and survival of mice expressing only zymogen-locked variant of prostasin (Prss8 R44Q). Indeed, HAI-2-deficient mice homozygous for R44Q mutation (Spint2-/-;Prss8R44Q/R44Q) are born in the expected numbers and do not exhibit any obvious developmental abnormality at birth. However, postnatal growth in these mice is severely impaired and they all die within 4 to 7 days after birth due to a critical failure in the development of small and large intestines, characterized by a widespread villous atrophy, tufted villi, near-complete loss of mucin-producing goblet cells, loss of colonic crypt structure, and bleeding into the intestinal lumen. Intestines of Spint2-/-;Prss8R44Q/R44Q mice showed altered expression of epithelial junctional proteins, including reduced levels of EpCAM, E-cadherin, occludin, claudin-1 and -7, as well as an increased level of claudin-4, indicating that the loss of HAI-2 compromises intestinal epithelial barrier function. Our data indicate that the loss of HAI-2 in Prss8R44Q/R44Q mice leads to development of progressive intestinal failure that at both histological and molecular level bears a striking resemblance to human congenital tufting enteropathy, and may provide important clues for understanding and treating this debilitating human disease.

[Rotaviruses in human and veterinary medicine]. / Les rotavirus en médecine humaine et vétérinaire.

Rotaviruses are the commonest cause of diarrhea and are responsible for more than 25% of all deaths from diarrhea worldwide. Children become infected early in life and most infections in infants older than 3 months are symptomatic. These viruses account for 18 million cases of moderate or severe disease and 900,000 deaths each year. The incidence of rotaviral disease is similar in developed and developing countries but the number of deaths is higher in developing countries. Infections occur throughout the year in developing countries but are seasonal in developed countries, occurring mainly between October and March. The mean age at first infection is 6 to 9 months in developing countries and 9 to 15 months in developed countries. The greater severity of infections in developing countries is associated with malnutrition, lower hygiene standards and the lactose malabsorption and deficiencies of zinc and vitamin A that accompany diarrhea. Many mixed infections also increase the severity of the rotavirus infection. The clinical symptoms of the disease in hospitalized patients are diarrhea, vomiting and dehydration. There is more vomiting than with bacterial infections. The severity of the clinical symptoms depends on the virulence of different strains. The disease is more severe and persistent in patients with reduced immunity. Age also has an effect. All children may have rotavirus in their feces but the percentage of children developing diarrhea is highest at an age of 3 to 6 months and decreases steadily thereafter. Rotaviruses can survive in air and may remain on surfaces for several hours. They are thus often responsible for nosocomial infections. Rotavirus was first identified in cattle in 1969. The virulence of the strain and the age of the calf at infection are important in the pathogenesis of rotaviral infection in cattle. Replacement of villous enterocytes is slow in newborn calves. This means that newborn calves are susceptible to disease caused by strains that are only moderately virulent. They are, however, protected during the first days of life by antibodies transmitted via the colostrum. There is competition between the rate of replication of rotavirus and replacement of enterocytes in older animals so only more virulent strains cause diarrhea in six-week-old calves. Adult animals become resistant to disease, but not to infection. The rotavirus genome consists of 11 segments of double-stranded RNA. Genetic recombination between these segments occurs naturally and can be reproduced in vitro. Recombinants between human and bovine strains have been identified but the epidemiological importance of this is unknown. The genomic segments encode 6 structural proteins (VP) and 5 non-structural proteins (NSP). VP6, the major capsid antigen, present can be used to identify groups of rotaviruses. The presence of VP7 indicates that the virus belongs to the G (glycoprotein) group of serotypes. There are 14 G serotypes, 10 of which can infect humans. The four main G serotypes are G1 to G4, with G1 accounting for 60% of human serotypes. The presence of VP4 identifies the P (protease-sensitive) serotype. The serotypes have different geographic distributions with G1P8 responsible for more than 50% of epidemics worldwide. The WHO project for the control of rotaviral infections focuses on avoiding fecal contamination. This is achieved by ensuring high standards of food hygiene, sewage treatment and chlorinated running water and by introducing vaccination when vaccines become available. Recombinant animal (bovine or simian) and human rotaviruses are currently being tested in phase III studies. Attenuated live human viruses, including cold-adapted strains are being tested in phase I trials. The quadrivalent recombinant rhesuslhuman vaccine had only mild side-effects in children and was effective, giving 82-92% protection against severe diarrhea over two years and 50% protection on average. (ABSTRACT TRUNCATED)

Inoculation of neonatal gnotobiotic dogs with a canine rotavirus.

Neonatal gnotobiotic dogs were inoculated orally with a rotavirus isolated from a pup with fatal diarrhea, and in the gnotobiotic dogs, diarrhea was observed between postinoculation hours (PIH) 20 and 24. The diarrhea persisted through PIH 154, and inoculated pups had clinical signs of dehydration after PIH 24. Negative-contrast electron microscopy of the feces from inoculated pups revealed rotavirus particles from PIH 12 through 154. Using an indirect-fluorescent antibody test, serum rotavirus antibody was detected in inoculated pups by PIH 96. In the duodenum, jejunum, and ileum of inoculated pups, group-specific rotaviral antigen was observed within absorptive villus epithelial cells and mononuclear cells in the villus lamina propria with an indirect-fluorescent antibody test. Fluorescence was seen in the small intestine of inoculated pups killed by PIH 12 and was present in intestines of pups killed through PIH 154. Rotaviral antigen was also seen in the mesenteric lymph nodes of a few inoculated pups killed at PIH 48.

Gross and light microscopic lesions in neonatal gnotobiotic dogs inoculated with a canine rotavirus.

Gross, light microscopic, and morphometric changes were observed in the small intestines of 11 neonatal gnotobiotic dogs after oral inoculation with a canine rotavirus. Starting in pups killed at postinoculation hour (PIH) 24, gross changes consisted of moderate dilatation and thinning of the walls of the small intestine, hyperemia, and a moderate amount of semiliquid-to-liquid greenish-yellow intestinal contents. In the jejunum and ileum of inoculated pups killed from PIH 18 to 48, columnar villus epithelial cells on the upper one-third of the villus were necrotic, and foci denude of epithelium were seen on the upper regions of villi. Inoculated pups killed from PIH 24 to 72 had mild-to-moderate villus atrophy in the jejunum and ileum, villi covered with cuboidal-to-flat squamous-like epithelial cells, and absence of large, clear vacuoles in the jejunal and ileal villus epithelial cells similar to those seen in villus epithelial cells of 9 control pups. Microscopic sections of the jejunum and ileum from inoculated pups killed from PIH 72 to 154 showed slight-to-moderate villus atrophy, and the villi were covered with cuboidal-to-low columnar epithelial cells. Morphometric results indicated lower mean villus-crypt ratios in the duodenum, jejunum, and ileum of inoculated pups. In addition, the morphometry of the small intestine indicated that crypt cell hyperplasia occurred in the duodenum early during infection without obvious villus atrophy, and hyperplasia of the crypt cells in the jejunum and ileum was observed later during the infection.

Effect of parenteral vaccination of dams on intestinal Escherichia coli in piglets with diarrhea.

To evaluate the effect of widely used parenteral vaccination of dams against neonatal colibacillosis, the virulence factors of the intestinal Escherichia coli flora, namely, O serogroup, enterotoxin(s) produced (heat labile, porcine heat stable, and murine heat stable) and adhesins (K88, K99, and 987P antigens) of 149 piglets from different herds in Sweden were investigated. Three categories were investigated: healthy piglets, diarrheal piglets born to unvaccinated dams, and diarrheal piglets born to dams vaccinated with a polyvalent Formalin-killed whole-cell vaccine containing K88 antigen (Porcovac; Hoechst Pharmaceuticals, Hounslow, England). Piglets less than 1 week old and those 1 to 8 weeks old were evaluated separately. Diarrheal piglets less than 1 week old from vaccinated dams yielded a higher incidence of K99 antigen-positive E. coli of the murine heat-stable enterotoxigenicity type compared with piglets of the same age group from unvaccinated dams. The percentage of diarrheal cases from which E. coli lacking recognized virulence attributes were isolated was also higher in the former compared with the latter group. In the 1- to 8-week-old diarrheal piglets of vaccinated dams, the overall incidence, enterotoxigenicity type, and serotype of the E. coli isolates resembled those of diarrheal piglets less than 1 week of age from unvaccinated herds. Enterotoxigenic E. coli bearing 987P antigen detectable in vitro was rare. Most of the enterotoxigenic isolates lacking K88, K99, and 987P antigens produced only ST. The investigation pinpoints some of the inadequacies of vaccines of the type studied under field conditions.

[Calf coronavirus neonatal diarrhea. A literature review (author's transl)]. / La diarrhée néonatale due au coronavirus de veau. Une revue de la littérature.

Calf coronavirus neonatal diarrhea. A literature reviewThe importance of the calf coronavirus in the etiology of neonatal diarrhea of calves has been reported many times from various countries. A literature review concerning this virus is presented in this paper. A detailed description of the pathogenesis, clinical signs and lesions of the disease, as well as the morphological, physicochemical, biological and antigenic characteristics of the virus are presented. The immunity of the calf against this virus and the principal diagnosis technics are also discussed.

New strain of mouse hepatitis virus as the cause of lethal enteritis in infant mice.

A new strain of mouse hepatitis virus (MHV) was isolated from pooled gut suspensions from an epizootic of lethal enteritis in newborn mice. Negative-contrast electron microscopy showed an abundance of coronavirus particles in the intestinal contents and intestinal epithelium of moribund mice. We found no other virus in the epizootic. Dams seroconverted to MHV polyvalent antigen and to the agent isolated, but did not develop antibodies to other known mouse pathogens. Virus propagated in NCTC-1469 tissue culture produced enteric disease in suckling mice but not fatal diarrhea; the dams of these mice also developed antibodies to MHV and to the isolates. By complement fixation, single radial hemolysis, and quantal neutralization tests, we found the isolates antigenically most closely related to MHV-S, unilaterally related to MHV-JHM, and more distantly related to MHV-1, MHV-3, MHV-A59, and human coronavirus OC-43. We also studied cross-reactions among the murine and human coronaviruses in detail. Tissues of infected newborn mice were examined by light microscopy, thin-section electron microscopy, and frozen-section indirect immunofluorescence, revealing that viral antigen, virus particles, and pathological changes were limited to the intestinal tract. We have designated our isolates as MHV-S/CDC.

Experimental neonatal colibacillosis in cows: serological studies.

Serological studies of passive immunity in experimentally induced bovine colibacillosis was studied in a 41-cow university herd. Pregnant dams were antigenized prepartum with two injections administered by the subcutaneous and intrammamary routes with one of four vaccine preparations (killed bacteria, live bacteria, culture supernatant, or heart infusion broth [control]). The data indicate that 77% of the neonates born to vaccinated dams were strongly protected against oral challenge with Escherichia coli strain B-44. Bacterial agglutinin and passive hemagglutination titers of colostral whey directly reflected the efficacy of the vaccines. A notable decrease in the whey titers to somatic and capsular antigens occurred after heat treatment at 56 C for 30 min. Complicity of heat-liable immune factor(s) in protection from scouring was suggested. The nature of the protective antigen is not clearly defined by these studies but there is some evidence that the K antigen may play a vital role in this regard.